Magnetometer. Figure of Merit (FOM) A test will be flown on-site prior to the survey to determine the FOM of the installed magnetometer. The system will be flown on the four cardinal headings doing a pitch (5 degrees), roll (10 degrees), and yaw (5 degrees), maneuver on each. The FOM will be calculated by summing the absolute errors of each of the 12 maneuvers and will be less than 1.5nT. Lag test The magnetometer lag with respect to the GPS system will be determined prior to the survey by passes in opposite directions at standard speed and height over a clearly identifiable strongly magnetic object.
Magnetometer. The Lessee must use a proton precession, overhauser, or Cesium total field magnetometer to detect ferrous and other magnetically susceptible metals. The Lessee must tow the magnetometer sensor as near as possible to the seafloor, but no more than 6 m above the seafloor. The Lessee must tow the magnetometer sensor in a fashion that minimizes interference from the vessel hull and any other survey instruments. The Lessee must ensure that a depth sensor is attached to the magnetometer sensor and annotate each survey line with “tow sensor height off seafloor” and with the time that each survey line was started and ended. The Lessee must ensure that magnetometer sensitivity is one gamma (y) or one nano-Tesla (nT) or less, and that the data sampling interval does not exceed one (1) second. The Lessee must ensure that the background noise level does not exceed a total of 3 gammas peak to peak. The Lessee must ensure that data are recorded on a digital medium in such a way that they can be linked electronically to the positioning data. The Lessee must ensure that the recording scales are set no higher than 1,000-gamma and 100-gamma full scale, respectively. The Lessee must ensure that shot points and recorder speed are annotated.
